Bitcoin Signed Message sometimes produces bad signature about dartsv HOT 12 CLOSED

Fix merged to master. Release is tagged 0.4.1 and pushed to pub.dev.

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Find problem at transaction/transaction_output.dart calcVarInt function .

Use var tx = Transaction.fromHex(rawtx) , seems endian problem , try rawtx as below:

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

Then compare tx.uncheckedSerialize() == rawtx will return false.

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Thanks. Investigating now.

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pointycastle has been handed over to bouncycastle.org and is active again. see the new PR linked above

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TwoStack.org has now been upgraded to use PointyCastle 2.0.x. Closing issue.

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hi @stephanfeb , thanks for porting to pointycastle v2. however, i think the issue is not solved since the PR mentioned above has still not been merged? I ran the test @Dhuliang provided and that seems to still fail. However, I might fail to grasp the details :)

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The issue with calcVarInt is unrelated to the Bitcoin Signed Messages issue reported. The Signed Messages were affected by the encodeBigInt() function in PointyCastle. I've simply removed that dependency since the BigInt encoding is two's-complement and the requirement for Signature is just to convert the hex buffer being signed to a BigInt.

The calcVarInt issue reported by @Dhuliang happens when his provided "rawTX" is serialized and then deserialized. I've double-checked all my VarInt code. There are more than 1000 serialization/deserialization test vectors which run flawlessly with current VarInt calculations.

My suspicion is that the provided "rawTX" is malformed, and that my library serializes it correctly. @Dhuliang can you open a separate issue with more information e.g. what the source of the "rawTX" is, and how you created it ?

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thanks for explaining @stephanfeb !

btw, I also tested with a recent raw transaction and that test succeeded.

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Oh cool. Btw I've just release 0.4.0 to pub.dev. Please raise any issues you might encounter.

Cheers
Stephan

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TwoStack.org has now been upgraded to use PointyCastle 2.0.x. Closing issue.

Sorry to inform you but the issue has not been resolved by upgrading to use the new PointyCastle
Bad signatures still happen sometimes, here is an example so you can test yourself:

import 'dart:convert';
import 'package:dartsv/src/message.dart';
import 'package:dartsv/src/privatekey.dart';

void main() {
String message = '/ipfs/QmdwwGaAujZ2gkPPAfQZJ9jUKRBB7d67ttD6phwU8BmfGS';
String wifKey = 'L4TAY9FYkGzwnZ77WRXZzYXsViKjVN31LzNenYfLLrEiFxoZbmSn';

SVPrivateKey privateKey = SVPrivateKey.fromWIF(wifKey);
Message messageSigner = Message(Utf8Codec().encode(message));
String signature = messageSigner.sign(privateKey);
print(signature);

if (base64Decode(signature).length != 65) {
print('BAD SIGNATURE!!');
}
}

BAD signature: 'H5W9/hDsIu5DjlWtSYcHFQnuhZ+MKWJTF+5bm+KVwA4hy0ehn1AMLjlAMEVT6hLjKuNirrKUW6bJsxGFG06yYw=='
(notice the double == at the end)

GOOD signature should be:
'HwCVvf4Q7CLuQ45VrUmHBxUJ7oWfjCliUxfuW5vilcAOIctHoZ9QDC45QDBFU+oS4yrjYq6ylFumybMRhRtOsmM='

see my original comment on how to fix it.

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Thanks for the example code @WouterGlorieux . I've just merged a fix to master.
Can you have a go and see if this resolves your problem ? If yes I'll prepare a release.

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Thank you for the quick response @stephanfeb
Yes, this fix does resolve the problem.

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